Re tubing my svt.

[FletcherML]

Hey y'all. The time has come to put new tubes in my svt CL. I've got a matched sextet of tungsol 6550's. Is there anything specific I need to look out for when putting them in?
Thanks in advance
Fletch

 

[chaosMK]

I've retubed my power sections a few times. I just put 'em in (doesn't hurt to do a little cleaning and whatnot... make sure your amp is off & unplugged too). In my particular cases I was using Mesa heads that have a fixed bias and had tubes selected for their spec. You might have to bias your SVT.

I like the Tung Sol RI 6550s. They are a pretty hifi tube, somewhat flat along the frequency range. Probably a good choice for the SVT.

 

[JimmyM]

Just biasing, but nowadays that's pretty easy as long as each set of 3 tubes is matched. I might question the need for a full retube if only one is bad, but you already have the tubes so you might as well.

 

[FletcherML]

Thanks for the feedback guys!
That's what my initial thought was, just wanted to be sure I wasn't wrecking anything. I've swapped out one tube at a time on two different occasions. And they're all just garbage now. Time to start fresh.
I'll let y'all know how it goes

 

[jastacey]

I'd let the amp warm up for about 15-20 minutes before you set the bias

 

[matti777]

IIRC the old SVTs had 400 volts in the large capacitors. These are still live even when unplugged so be careful please. Better safe than sorry. The Tungsol 6550s are nice in my DB359.

 

[BassmanPaul]

Closer to 650-700V, certainly not just 400V

 

[matti777]

Closer to 650-700V, certainly not just 400V

even less reason to poke around with a screwdriver

 

[hodgy]

It's a CL, not an old school SVT. If it's a matched set, just throw them in, be careful you don't bust the plastic key, turn on, warm up, set your bias so both lights are green. Plug in, turn up, scare the neighbors and enjoy!

 

[Cartoonist]

Always a good idea to spray a little contact cleaner on the pins before putting them in, but not that critical really.

Also, the first time you use them it might pay to start with a cold bias for half an hour or so before winding the bias pots up until the LEDs go green (check this when the volume's down with no signal going through).

And check the bias regularly as it can shift over time.

Any other problems consider changing your driver or PI tubes as they cop a fair thrashing. These are much cheaper than your 6550s.

 

[FletcherML]

Sounds good everyone. I really appreciate you guys throwing in the advice. The tubes are on their way to my house now. Stoooked